Stop in for a cup of coffee

I think it's the shape of the tank The rectangle shape would work if the tank was the same shape.
Prob dead on in a rectangular tank. The fuel senders were one of the systems I had to work on. Pretty interesting a bunch of tubes with a smaller tube in it usually 4 or 5 in a c-130 tank so when it banked the fuel level sent the same capacitance to the gauge. Ony way they ever failed was a wire came off usually after someone was in the fuel tank and the wires got pulled.